Is silver nitrate an effective means of pleurodesis?

A best evidence topic was written according to a structured protocol. The question addressed was whether silver nitrate (SN) is an effective means of pleurodesis. A total of 42 papers were identified using the reported search, of which 8 represented the best evidence to address the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Three studies assessed the efficacy of SN in inducing pleurodesis in patients with malignant pleural effusion (MPE). Using intrapleural injections of SN in concentrations of 0.5-1%, they reported success rates of 89-96% at 30 days. One of these studies compared SN with talc slurry and found equally effective pleurodesis at monthly intervals up to 4 months (P = 0.349-1). Another two studies retrospectively reviewed the efficacy of thoracosopic SN instillation (1 or 10%) in patients with primary spontaneous pneumothorax (PSP). Recurrence rates were 0-1.1% during long-term follow-up. One of these compared SN with simple drainage and reported a therapeutic gain of 45 ± 30% (95% CI) with SN, at the cost of increased analgesia consumption, chest drainage and hospital stay. Finally, three studies reported the results of the comparison of intrapleural injections of SN, talc or tetracycline in inducing pleurodesis in rabbits. SN was equally effective with tetracycline and superior to talc at producing pleurodesis, with lower concentrations of SN (0.1%) resulting in significantly attenuated systemic inflammatory response when compared with either higher SN concentrations (0.5%) or talc. Although not commonly used, available evidence suggests that SN is an effective agent in inducing pleurodesis in patients with either MPE or PSP. Compared with universally employed talc, it seems to result in at least similar short-term recurrence rates for MPE, with a demonstrably good side-effect profile; the longer-term efficacy is, as yet, undetermined. In cases of PSP, evidence suggests that thoracoscopic SN instillation is at least as effective as talc, with potentially fewer systemic side effects.